Comparison and standardization of measurement of anti-acetylcholine receptor antibody between laboratories

The presence of autoantibodies to the acetylcholine receptor (anti-AChR) is useful in the diagnosis of myasthenia gravis, and their titre correlates with severity of the disease. Standardization of their measurement is therefore clinically important. Six laboratories world-wide were asked to determine anti-AChR under local conditions in coded samples and to repeat the measurement on the same samples recorded. There was a high degree of consensus over rank order of the samples but a wide systematic variation in the titres obtained. Standardization of units is an important next step in improving the comparability of anti-AChR data between laboratories.